Lecture 5: Skeletal System Flashcards Preview

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Flashcards in Lecture 5: Skeletal System Deck (85):
1

Fuctions of skeletal system

protection, support, leverage, Storage, blood cell formation

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Fuctions: Protection

-CNS protected by skull and vertebrae
-heart and lungs protected by rib cage
-internal urogenital system by pelvis

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Fuctions: Support

-giving rigitdity and form to body
-maintain upright posture
-gives basis for external structure
-apperance of most animals

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Functions: Leverage

-mechanism that augments speed of movement or force
-levers are mainly the long bones of the body and the axes are joints where bones meet
-aids in locomotion, defense, offence, and grasping

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Fuctions: Storage

-Minerals like calcium and phosphorus

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Functions: Blood cell formation

aka hematopoiesis takes place in the cavities of bone(bone marrow) and in fat

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Compact bone/Cortical Bone

-hard layer of bone
-solid, strong, resists bending (cortex and surrounds spongy bone)
-covers most bone
-forms most entire surface of long bone

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Cancellous bone/Spongy bone

-composed of spicules
-arranged to form a porous network filled with marrow
-located in epiphysis, metaphysis and right outside the medullary cavity

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epiphysis

either extremity/end of long bones

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diaphysis

cylindrical shaft of long bone stituated between the two epiphysis

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metaphysis

the most recently form bone at area on either end of the diaphysis, filled with spongy bone, right before epiphysis

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epiphysis cartilage

-layer of hyaline cartilage separating the epiphysis and diaphysis of a immature bone
-site of bone growth

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articular cartilage

thin layer of hyaline cartilage that covers the articular surface of bone

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articular projections: head

-spherical projection, ie head of femur

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articular projections: condyle

cylindrical/rounded process of bone that articulates with another bone
ie. distal end of femur

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articular projections: trochlea

pully-like articular mass
ie. distal end of femur or humerus

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articular projections: facet

small, flat, smooth surface of bone, generally an articular surface
ie. articular facet of adjacent carpal bones

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non-articular projection: process

general term for a bony projection/prominenece
ie spinous process of vertebrae

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non-articular projection: tuberosity

-large, non-articular projection
-or a raised section of bone to which a ligament, tendon, or muscle attaches
-usually created or enlarged by the stress of the muscle's pull ont that bone during growth

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non-articular depressions: Fossa

large, non-art. depression; shallow depression or hollow
ie. atlantal fossa ventral to wing of atlas

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non-art. depression: fovea

small non-art. depression
ie. head of femur

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non-art. depression: foramen

-hole in which bone through which nerves or vessels pass
ie. foramen magnum

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nonart. depression: spinal canal

tunnal through one or more bones
-ie. spinal canal

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articular depression: glenoid cavity

shallow articular cavity
-ie articular surface of scapula

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art depression: cotyloid cavity

deep art cavity
ie acetubulum of hip

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art depression: notch

articular indentation
ie semilunar notch of the ulna

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Long Bones

-greater in one dimension
-grows in length ONLY at epiphyseal cartilage
-functions as levers, support, locomotion, grasping
-ie humerus, radius, ulna, metacarpal

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Short Bones

-equal in all dimensions
-interior filled with marrow space
functions as shock absorbers
located in complex joinst
ie carpals and tarsals, consists mainly of spongy bone covered with a thin layer of compact bone
function to allow movement, provide elasticity, flexibility, and shock absorption

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Flat bones

relatively thin, expanded in two dimensions
protect vital organs
provides attacment site for muscles
ie Ribs, ilium, sternum, and scapula
consist of two layers of compact bone, with spongy bone and marrow in between

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Sesamoid bones

resemble sesame seeds
short bone embedded within a tendon or join capsule
ie patella/kneecap; function to alter the angle of insertion of muscle

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Pnematic bones (aka air bones)

contain air spaces or sinuses that communicate with exterior
ie frontal bones and maxillary bones of skull

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axial skeleton

skull, vertebrae, ribs, not-limbs

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skull

protects the brain
supports many sense organs
forms passages for beginning of digestive and respiratory systems

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Vertebral column

-median, unpaired, irregular bones
C=cervical/neck, T=thoracic/chest, L=lumbar/loin, S=Sacral/pelvis (fused), LS=fused lumbar and sacral (fowl), CD=caudal/tail

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vertebral formula

cow: C7, T13, L6, S5, CD18-20
human: C7, T12, L5, S5, CD4

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Sternum and ribs

sternum form floor of bony thorax
gives attachment site to costal cartilages of sternal (true) ribs
forms place of origin for pectoral muscles

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appendicular skeleton

pectoral limbs, including scapula
pelvic limbs, including pelvic bones

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composition of bone

2/3 inorganic components deposited within organic framework
mainly calcium and phosphorous salts
gives hardness and rigidity

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altered composition of bone

INORGANIC=RIGIDITY
'minus' inorganic component=original shape is retained but flexible enough to tie into a knot
ORGANIC=TOUGHNESS
'minus' organic component=original shape but becomes very brittle and easily broken

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Ossification

process of bone formation
osteoblasts lay down osteoid tissue
calcified under influence of phosphatase
centre of ossification is the localized area of bone formation

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Types of ossification

dependent on environment
1. heteroplastic ossification
2. intramembranous ossification
3. endochondral/intracartilagenous ossification

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heteroplastic ossification

bone formation in tissues other than skeleton
ie os penis in dog, os cardis in bovine heart, pathological ossification

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intramembranous ossification

bones that originate between sheet-like layers of connective tissues, ie. broad flat bones of skull
-membrane like layers of primitive connective tissue appear at sites of future bones
-primitive connective tissue cells arrange around blood vessels in these layers
-connective tissue cells differentiate into osteoblasts, forming spongy bone
osteoblasts become osteocytes when bony matrix completely surrounds them

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Osteoblasts form _____ and become.....

form spongy bone
become osteocytes when bony matrix completely surrounds them

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intramembranous ossification process

-connective tissue on surface of each developing structure forms a periosteum
-osteoblasts on the inside of the periosteum form compact bone over the spongy bone

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endochrondral ossication

-bone is preformed in cartilage in the fetus
-most LONG BONE is developed this way
-the cartilage becomes mineralized and replaced by bone tissue
-the long bone can continue to grow in length if the cartilage between the epiphysis and diaphysis continues to grow
-when all this cartilage has changed to bone, increase in lengthis impossible

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endochondral ossification growth in diameter

-long bones increase in diameter by producing new bone from the periosteum
-as new bone is laid down, portion of deeper bone are removed to increase the marrow cavity
-most notable in fetus' cartilage pattern being replaced by bone

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growth of an endochondral bone/long bones

-bones grow in length at the epiphyseal plates, the junction of diaphysis and epiphysis. these junctions are known as metaphyses
-cartilage cell multiplication in the zone of growth will force the epiphysis away from the diaphysis, thus lengthening the epiphysial plate
-subsequent removal of cartilage and deposistion of bone in the zone of ossification in turn will lengthen the diaphysis
-diameter increases from activity of the osteogenic cells in the periosteum

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epiphyseal plate divides into

zone of growth
zone of cartilage formation,
zone of ossification

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Bone matrix of osteoid tissue

-highly sensitive to environmental changes like pressure, blood supply, and nutrition
-can decrease/increase in size
-capable of withstanding tension (stretching), compression, bending, and tortion

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Bone Fractures: types

fracture is a break in the continuity of a bone
includes simple, green stick, compound, epiphyseal, and comminuted

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simple bone fracture

skin over fracture site unbroken

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green stick fracture

one side of bone is broken and other side is intact, often seen in young animals

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compound fracture

a wound from the exterior contacts the bone; bone pierces the skin

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epiphyseal fracture

fracture at the junction of epiphysis and diaphysis; common in young animals

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comminuted fracture

number of small fragments formed at fracture site

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fracture healing

-fractures destroy blood vessels carrying nutrients to osteocytes, initiating repair sequence (early fracture to inflammatory phase)
-callus-specialized repair tissue binds broken ends of fracture together (well formed callus/reparative phase)
-fracture hematoma-blood clot occurs immediately after the fracture, then reabsorbed and replaced by callus (remodelling phase)
-callus then becomes mineralized
-reorganization of callus and formation of bone shaft and marrow cavity completes the repair

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Pathological bone conditions

tuberculosis: bacterial infection
osteomyelitis: inflammation of bone and marrow
osteoma: bone tumor; ie. exostoses, chondroma, fibroma, osteoclastoma
rickets
achondroplasia

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Joints

Articulation between bones
-binds part of skeleton together
-allows bone growth
-permits parts of the skeleton to change shape during childbirth
-enables body to move in response to muscle contractions

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classification of joints (by degree of movement)

1. synarthrotic: immovable
2. Amphiarthrotic: slightly movable
3. diathrotic: freely movable (consists of articular cartilage, a joint capsule and synovial membrane); limb joints

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class of joints (by type of tissue binding bones): fibrous joins

united by fibrous tissue
contains no joint cavity
syndesmosis: amphiarthrotic splint bones of horse
suture: synarthrotic bones of skull
gomphosis: synarthrotic articulations of teeth in jaw sockets

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cartilaginous joints

united by cartilage, contains no joint cavity
synchondrosis: synarthrotic hyaline cartilage joints; the union of diaphysis and epiphysis of immature ebone
symphysis: amphiarthrotic pelvic bones and vertebrae

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Synovial (diarthrodial) joints

surrounded by thick flexible membrane forming a sac filled with lubricant for joints
articular surfaces, articular cartilages, articular cavity, joint capsule, and ligaments make them up

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structure of synovial joint: articular cartilage

resists wear and minimizes friction when compressed as the joint moves

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synovial joint: subchondral plate

bone beneath the articular cartilage (cancellous-spongy bone), somewhat elastic and absorbs shocks

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synovial joint: joint capsule

outer fibrous connective tissue
-helps bind the articular ends of bone together

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synovial membrane

inner layer of joint capsule of loose connective tissue
secretes and reabsorbs fluids

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synovial cavity

closed sac surrounded by synovial membrane
secretes clear synovial fluid that moistens, lubricates, and supplies nutrients to articular cartilage

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synovial joint: menisci (fibrocartilage)

disks of fibrocartilage located between articular surfaces
absorbs shock and provides cushioning

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synovial joint: bursae

closed, fluid filled sacs

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types of joint movement

gliding, angular, rotation, and circumduction

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gliding

simplest type of joint motion
one surface moving over another without rotary or angular motion
exists between two adjacent surfaces

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angular movment

decreases or increases the angle between two adjoining bones
includes flexion, extension, hyperextension, abduction and adduction

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angular motion: flexion

decrease in angles, ie bending of arm or leg

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angular motion: extension

increasing angles: straightening or unbending of leg or arm

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angular motion: hyperextension

angle between segments beyond a straight line, like fetlock joint in horses

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angular motion: abduction

moving and extremity away from body (wings up)

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angular motion: adduction

bringing extremity towards body (wings down)

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Rotation movement of joints

movement in which bones move around a central point without being displaced
ie; turning the head from side to side

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circumduction

movment of the hips and shoulders

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Other types of joint motion: pronation and supination

pronation: turning downward; placing palm down
supination: turning upward; placing palm up

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other joint motion: eversion and inversion

eversion: turning sole of foot outward
inversion: turning sole of foot inward

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Joints of axial skeleton: skull

mainly sutures which ossify with age, fontanel of baby's skull
symphysis of mandible
sychondrosis: junction of sphenoid and occipital bone at base of skull

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joints of axial skeleton: first movable joint

the temporomandibular joint

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injuries and pathological dirorders of joints

dislocation: stretching or tearing of ligaments, tearing of join capsule
subluxation: partial dislocation
arthritis: inflammation of joints
fractures involving joints
thoroughpin: swelling of digital flexor tendon
laminitis: inflammatory disease of hooves